Many kinds of consumer products are packaged in flexible pouches including dispensable plastic bags and blister packs of commonly known types. This is true for items such as confectionery and snack products and also for various types of medicinal aids and drugs conventionally marketed over the counter.
For example, for candy, a flexible package is used with crimped end seals and a longitudinal fin seal. This type of package is advantageous in that it can be made virtually airtight and moisture-tight due to the nature and configuration of the seals.
In connection with the blister type package, a flexible lid is applied to the blister package and is sealed around its peripheral edges to enclose the objects within the cavity of an expanded blister. The more rigid puncture resistant and collapse resistant blister aids in the protection of the items packaged therein.
The difficulties with both of these types of packaging concepts is that they are difficult to open to gain access to the items contained therein and they are also incapable, or at least difficult, to reclose when the package has been partially emptied.
In order to maintain the advantages of the flexible and blister type of packages for the consumer market, various types of materials and structures have been developed over the years.
For example, Australian Patent No. 152,213 is an early example of a flexible sheet of wrapping paper with a moisture-proof outer surface and a cohesive under surface. In this instance, the wrapping material is paper with a waxed outer surface and a latex coating on the inner surface. U.S. Pat. No. 2,432,075 shows a similar concept with the paper containing a cellophane-like outer surface and a latex coated inner surface.
The concept of the use of a material for packaging purposes formed of a polymer film and having linear tear properties is present in U.S. Pat. No. Re. 30,726.
U.S. Pat. No. 4,516,675 extends the wrapping sheet concept to a multi-layer arrangement of plastics and chemicals for purposes of providing a tamper-proof package. The consideration of providing a child-proof or tamper-proof mechanism as part of the packaging structure has further complicated the packaging design field. Accordingly, in addition to giving consideration for ease of opening of the package and the ability to reclose the package, on many occasions it is desirable to provide means for permitting easy access, but providing means for making it difficult to tamper with the package and adulterate the contents. Additionally, in many instance it has become desirable to provide child-proof means to the package while still facilitating ease of opening an access to adults.
U.S. Pat. No. 2,105,367 discloses an early means for providing a flexible wrapper which includes a preformed structure to facilitate opening of the package. In this instance, zones of weakening are provided in the form of notches and a tab to pull a portion of the wrapper in a predetermined direction to tear open the package and permit ease of access.
A further extension of this idea appears in U.S. Pat. No. 3,540,579 where a flexible membrane covers one side of a packaged item and a rigid backing material protects and covers the other side. Bending of the backing material projects the packaged item through the membrane side by bursting the membrane in a predetermined manner.
Other opening aids appear in U.S. Pat. Nos. 3,608,815; 3,980,224 and 4,200,200. U.S. Pat. No. 3,608,815 utilizes an oriented film as part of packaging material whereby the material is minutely expanded at a plurality of points so that a pattern is located on a fold in the material which permits and facilitates grasping and tearing for purposes of opening the package.
U.S. Pat. No. 3,980,224 introduces the use of a tab as part of a package lid including a laminated composite of a uniaxially oriented film and a biaxially oriented film whereby pulling of the tab will open the lid in the uniaxially oriented direction.
U.S. Pat. No. 4,200,200 shows the use of a axially oriented film to facilitate opening of a container by finger pressure to provide a straight line slit in the film. Thus, the axially orientation of a film material facilitates ease of opening in one direction.
As indicated by U.S. Pat. No. 4,200,200, the use of various types of materials to facilitate ease of opening of packaging has been extended to other types of packages than merely flexible wrapping materials.
For instance, blister type packaging has become quite common and examples of background developments in this area can be observed in U.S. Pat. Nos. 3,078,986; 3,941,248; 4,196,809; 4,211,326; 4,233,326; 4,280,621; and 4,398,634.
The blister package of U.S. Pat. No. 3,076,986 teaches the use of a polyethylene coversheet adhesively secured to the blister container with a cutaway corner to facilitate grasping and removal of the lid.
U.S. Pat. No. 3,941,248 is directed to a child-proof or tamper-proof structure where zones of weakening are provided to facilitate breaking away of a single compartment from the remaining compartments. A flexible cover foil is applied to a blister pack container.
U.S. Pat. No. 4,196,809 is also directed to a child-resistant package in a blister pack configuration. A multi-layer flexible cover lid is employed with the layers interconnected so that folding of a corner of the package will cause the layers to separate and facilitate opening to gain access of the contents of the blister package.
The blister package of U.S. Pat. No. 4,211,326 includes a multi-layer lid with one of the laminations of the lid being of a partially-oriented polymeric material. The objective is to enhance the moisture barrier properties, clarity and strength in the thermo-formed state.
U.S. Pat. No. 4,233,326 shows a packaging structure for confections which provides means for ease of access to individual items of a group of items packaged together.
U.S. Pat. Nos. 4,280,621 and 4,398,634 are both directed to child-proof blister packs which also include some of the features discussed above. For example, in U.S. Pat. No. 4,280,621 a laminated cover material is positioned over the blister pack with the layers adapted to be separated to facilitate opening of the package. Folded portions provide indicia for locating the separation point for the layers. U.S. Pat. No. 4,398,634 employs the concept of portions of relief in the form of slits or cuts which directs the user to the proper location for opening of the package or removal of individual units therefrom.
The idea of being able to reclose a package has been of concern for many years. For example, U.S. Pat. No. 1,992,152 deals with the difficulty in reclosing a rubber tobacco pouch. The rubber liner is designed to have tacky portions thereof brought in contact with each other to perform a closure step. The tacky portions are located at a predetermined position on the inner surface of the pouch and permit distortion of the pouch to engage the adhering portions and close the pouch.
A similar concept appears in U.S. Pat. No. 3,735,918 where the container is Provided with a series of crossing bands of cohesive material coated on the body and flap of the pouch. Folding of the pouch will cause the cohesive bands to contact one another and reseal the container.
A pressure sensitive adhesive is used in the reclosable package of U.S. Pat. No. 3,613,874 for purposes of permitting resealing of the flexible container.
In connection with the above references, there are used many different types of polyolefin films for flexible wrapping materials in the packaging art, either as an individual wrapping material or in a laminated form. It is also been shown how the linear tear properties of an oriented polyolefin film can be used to advantage. For example, an example of the construction of that type of material appears in U.S. Pat. No. 4,098,406.
As opposed to actual packaging, foamed stretched uniaxially oriented polyolefin film material with a pressure sensitive adhesive coating on its underside has been used for labels. For example, U.S. Pat. No. 3,854,581 is of interest in this respect.
However, there is still need for improvement in respect to tear oriented packages, in respect to integrity of the package, ease of opening, tamper and child resistance, and recloseability.